DESCRIPTION: (Applicant's Abstract) This is a collaborative proposal to extend and refine a simple dynamical model of adaptive and maladaptive motivated behavior (feeding, drug addiction). There are strong linkages at several levels between feeding regulation, habituation, and food-reinforced operant learning. There are also suggestive resemblances between the regulatory features of feeding and drug addiction. We have shown that very simple multiple-time-scale (MTS) models can simulate the major dynamic properties of feeding regulation, simple habituation and some aspects of operant choice behavior. We propose to extend and test a family of MTS models with data sets from all three areas. Our aim is to use insights gained from the study of feeding regulation and habituation to expand our understanding of the dynamics of addiction. We contend that a thorough under-standing of dynamics at the level of behavioral data is an essential foundation for advances in our knowledge of the neurophysiological and neuropharmacological bases of addiction and motivated behavior generally. This proposal is relevant to following basic behavioral sciences topics under the RFA: learning and memory, animal learning and behavior, and the motivational and learning processes underlying craving.